When you're working with others in a networked environment, you may want to share workbooks you created. You may also want to share the responsibilities of entering and maintaining data. Sharing means users can add columns and rows, enter data, and change formatting, while allowing you to review their changes. This type of work arrangement is particularly effective in team situations in which multiple users have joint responsibility for data within a single workbook. In cases in which multiple users modify the same cells , Excel can keep track of changes, and you can accept or reject them at a later date.
Enable Workbook Sharing
Change Sharing Options